SPA-Aeronomy [SA]

 CC:Hall E  Wednesday  0800h

Recent Advances in Understanding the Ionospheric Response to Variable Drivers II Posters

Presiding:  D Knudsen, University of Calgary; O de la Beaujardiere, AFRL RVBXP



* McCanney, J M (, INDEPENDENT SCIENTIST, P O Box 186, Mound, MN 55364, United States

Most earth weather and ionosphere-space environment coupling studies separate the problems into distinct groups. Heliosphere to solar wind - solar storm activity to ionospheric coupling - thermosphere and mid- altitude to the ionosphere and electrical effects such as elves and sprites and thunderstorms in another group - additionally mid and high latitude weather systems are many times separated also. The theoretical work here shows that not only are these areas coupled and related, but it also shows that without the constant electrical and resulting magnetic driving forces from space environments, earth would have little if no weather variability at all below the ionosphere. With only solar light energy as input, earth (and the other planets) would have little weather at all. The realization that extensive electrical activates occur in and above the troposphere, extending to the ionosphere and ultimately coupling to the magnetosphere have raised the theoretical and experimental questions regarding the sources of EMF which create the observed effects. The current work has identified 17 Local Electrical Batteries (LEBs), which provide the electrical EMF that can be linked to the observed effects the jet streams and lower atmospheric weather phenomenon. The path of the sources of EMF can be followed from the passing solar wind through "tunnels" that end in electrical currents that pass into the atmosphere via the ionosphere to storm cloud systems in the lower atmosphere. However the source of energy comes from localized plasma discharging of a non-uniform plasma environment that powers the electrical systems of the entire solar system. These are ultimately the sources of electrical energy that power the severe lower atmospheric storm systems such as westerly moving hurricanes at low latitudes and associated tornadoes. The connection is made theoretically with the solar wind that drives the 17 identified LEBs. The ultimate source of driving energy is the result of an excess current of protons in the solar wind, which creates an overall capacitor with inherent non-uniform electric field surrounding the Sun. On a local scale the voltage gradients are quite low, but all objects in this solar capacitor, including the planets and their moon systems, discharge this capacitor over extensive trans-planetary distances, thus creating excessive current flows, which also respond to CMEs and solar flares which carry a far greater potential gradient in the passing solar wind. The key to understanding reactions to non-uniform electric fields in the LEB environment is based on the fact that planetary Debye shielding takes on a new form, which is extended from that of the neutral environment typically considered in previous theoretical models. An attempt is made to solve the fundamental problem of the source of energy that drives these systems. The effects of moons and their positions relative to the planet and solar wind, as well as multiple planetary electrical alignments, are shown to contribute to the overall discharge phenomenon. A connection is made between these energy sources and cyclonic storms, earthquakes and volcanic "trigger" mechanisms. The goal of this research is to create an overall space weather model that couples the single energy source (the non-uniform plasma environment of the Sun created by an excess current of positive charge in the solar wind) to the earth's magnetosphere and ionosphere (and other planetary environments) and ultimately to the low altitude weather systems.


Topside Ionospheric Profile Constructed with ROCSAT Observation and Jicamarca Ionosonde Data

Tulasi Ram, S (, Institute of Astronomy and Astrophysics, Academia Sinica, 128 Academia Rd., Nankang, Taipei, TW 115, Taiwan
* Su, S (, Institute of Space Science, National Central University, 300 Chung-Da Rd., Chung-Li, TW 320, Taiwan
Liu, C (, Academia Sinica, 128 Academia Rd., Nankang, Taipei, TW 115, Taiwan

Topside ionospheric profile is constructed using simple Chapman-alpha function to connect the ROCSAT observed density at the 600-km altitude to the bottomside ionosphere measured by the ionosonde at Jicamarca. We found that the constructed topside density profiles are almost identical to the Jicamarca ISR measurements in several examples and are all superior to other approaches such as the Huang-Reinisch method and the IRI 2007 model. The local time variation of the effective topside scale height in the Chapman- alpha function for the December solstice in 2003 indicates a low ion temperature in the morning hours that is quite different from the ion temperature measured by ROCSAT at the 600-km altitude where the temperature rises rapidly at sunrise. The discrepancy between the two temperatures can be explained by the vertical variation in the topside ionospheric temperature during the morning hour and is confirmed from a result in the SAM2 model.


The variation of Ionospheric Slab Thickness Parameters and Comparison with IRI in Mid- Latitudes During Solar Maximum

* Chuo, Y (, Department of Commercial, Technology & Management, No.1, Ling-tung Rd., Ling-Tung University, Taichung city, 408, Taiwan
Lee, C (, General Education Center, Ching-Yun University, Jung-Li, 320, Taiwan
Cheng, W (, Institute of Space Science, National Central University, Jung-Li, 320, Taiwan

This study presents the diurnal, seasonal and solar flux in ionospheric slab thickness (τ), button slab thickness (B0) and the peak height (hmF2) during solar maximum in mid latitudes. The data of foF2, hmF2 and B0 with 15 mimutes interval resolution are measured by the UMLCAR SAO-Explorer at the mid latitude digisonde station Wuhan (30.6oN, 114.4oE). The GPS-derived total electron content (TEC) data are measured at the Wuhan receiver (30.53oN, 114.360E) to study the variations in slab thickness of ionosphere during April, 1999 - March, 2000, corresponding to the solar maximum phase. Meanwhile, the study also make a comparison which are mad with International Reference Ionosphere model (IRI-2001) using both the standard B0 and the Gulyaeva's B0 thickness. This study shows the daily, seasonal, and solar flux variations and comparison with IRI-2000 model during solar maximum phases.


Comparison of two phase scintillation estimators for GPS data obtained from High Latitudes.

* Mushini, S C (, Department of Physics, University of New Brunswick, Fredericton, NB E3B5A3, Canada
Thayyil, J P (, Department of Physics, University of New Brunswick, Fredericton, NB E3B5A3, Canada
Langley, R B (, Department of Geodesy and Geomatics Engineering, University of New Brunswick, Fredericton, NB E3B5A3, Canada
MacDougall, J W (, Department of Electrical Engineering, University of Western Ontario, London, ON N6A 5B9, Canada

Radio waves propagating through small scale plasma density irregularities produce fluctuations in both amplitude and phase of the signal. These fluctuations are called ionospheric scintillations. Due to their spatial diversity, GPS satellites allow scintillation measurement from different azimuthal sectors. Reliability of derived scintillation indices depend on the scintillation estimators used. Here we compare two different estimators for phase scintillations for data obtained from Canadian High Arctic Ionospheric Network (CHAIN) GPS receivers at high latitudes. These stations are specifically chosen to represent polar cap, near to the auroral boundary, and sub-auroral regions . Results of the comparison and its implications will be discussed.


Latitudinal Quiet Time Variations of Ion Drifts in the Ionosphere at Low- and Middle- Latitudes

* Pacheco, E (, W.B. Hanson Center for Space Sciences, University of Texas at Dallas, WT15, Box 830688, Richardson, TX 75083-0688, United States
Heelis, R A (, W.B. Hanson Center for Space Sciences, University of Texas at Dallas, WT15, Box 830688, Richardson, TX 75083-0688, United States
Su, S (, National Central University, 300 Jhongda Rd, Jhongli, 32001, Taiwan

There is limited knowledge of the latitudinal (apex-height) variability of ion drifts at low and middle latitudes. This study provides a global description of the ion drifts that are key elements for the understanding of the dynamics of the ionosphere and are important parameters for physics-based models. We use measurements from the ROCSAT-1 satellite for the years 2000-2003 and for altitudes near 600 km. Offsets in the original data are removed by considering separately the northbound and southbound passes, and enforcing conjugacy on the derivation of ion drifts perpendicular to the magnetic field. Our study investigates latitudinal, longitudinal and local time variations of ion drifts in the topside ionosphere for a geographic latitude range from - 25° to +25°. Specifically, we derive the ion drifts in the directions parallel and perpendicular to the magnetic field during quiet times defined when the Dst index is greater than -100 nT and the Kp index is equal to or less than 3. We then describe the longitude differences in latitude and local time profiles of the ion drifts.


Observations and Theoretical Predictions for Decameter Auroral Electrojet Irregularities

Moorcroft, D R (, The University of Western Ontario, 1151 Richmond Street, London, ON N6A 3K7, Canada
* Kagan, L M (, The University of Western Ontario, 1151 Richmond Street, London, ON N6A 3K7, Canada
Kissack, R S (, The University of Western Ontario, 1151 Richmond Street, London, ON N6A 3K7, Canada

Recent theory and its application to experiment [1-3] shows that the wavelength dependence of threshold phase velocities of Farley-Buneman waves has a rich dependence on a variety of physical conditions and processes, including thermal transport, etc.  It is therefore of interest to extend the comparison of theory and experiment into the HF radar range, where comparisons have not yet been made.  There are many SuperDARN radars operating in this frequency range in the northern hemisphere. Of all of these, the most suitable for the observation of Farley-Buneman instabilities is the Pykkvibaer radar, as it looks directly along the auroral electrojet for much of the day. We have made use of multi-frequency observations made with the Pykkvibaer radar to test the dependence of phase velocity of Farley-Buneman waves on radar frequency as predicted by the Kagan and Kissack [2] and Kissack et al. [3] theories. We have found qualitative agreement between the observed and predicted frequency dependence for slightly disturbed conditions. [1] Kagan, L.M., and J.-P. St.-Maurice, J. Geophys. Res., 109( A12), A12302, 2004. [2] Kagan, L. M., and R. S. Kissack, Geophys. Res. Lett., 34, L20806, doi:10.1029/2007GL030903, 2007. [3] Kissack, R.S., L.M. Kagan, and J.-P. St.-Maurice, Phys. Plasmas, 15, 022902, 2008.


Effects of Polar Cap Absorption of Energetic Particles on December 2006

* Dmitriev, A V (, Institute of Nuclear Physics, Moscow State University, Moscow, 119899, Russian Federation
* Dmitriev, A V (, Institute of Space Science, National Central University, Jungda Rd. 300, Chongli, 32001, Taiwan
Yeh, H C (, Institute of Space Science, National Central University, Jungda Rd. 300, Chongli, 32001, Taiwan
Tsai, L C (, Center for Space and Remote Sensing Research, National Central University, Jungda Rd. 300, Chongli, 32001, Taiwan

Ionization effects produced at the northern polar ionosphere and upper atmosphere by energetic particles during December 2006 were studied. That period was accompanied by several solar flares and solar energetic particle (SEP) events as well as by several weak and one strong magnetic storms. Fluxes and spectra of energetic protons and electrons precipitating to the high-latitude and polar regions were measured by a constellation of four POES satellites at low-altitude orbit. The precipitating particles of solar, interplanetary and magnetospheric origin demonstrate different spectral properties and spatial distributions that permit us to study their dynamics separately. Magnetospheric particles are electrons having soft spectra and precipitating predominantly at auroral ionosphere. SEP together with particles accelerated at leading edge of interplanetary transients are characterized by higher energies and harder spectra. They penetrate to the magnetosphere in the polar cap region and causing abundant ionization of the lower ionosphere and upper atmosphere. Using POES data and standard models of the ionosphere and atmosphere we calculated height profiles of specific ionization produced by the SEP in the polar cap. The dynamics of SEP ionization reveals three intensifications at heights from 50 to 100 km in 7 to 8, 13 and 14 December. At the same time the ionization was measured as electron content (EC) by the COSMIC/FORMOSAT-3 constellation of six satellites. That experiment provides a 3- D tomography of the ionosphere and upper atmosphere on the base of radio occultation technique, which makes use of radio signals transmitted by the GPS satellites. We found that the observed temporal and spatial patterns of EC are pretty close to the dynamics of specific ionization, produced by the SEP and in particular by the electrons. Namely, the spatial region of enhanced ionization is overlapped pretty well with the enhancements of the electrons penetrating to the bottom ionosphere and upper atmosphere. The importance of energetic electrons in the polar cap absorption effects is discussed.